(1) Field of the Invention
The present invention relates to an image forming apparatus including a fixing device, such as a printer or a copier, and in particular to a technology for preventing residual toner remaining after transfer from being fused onto an image carrier by heat generated from the fixing device.
(2) Description of the Related Art
An image forming apparatus, such as a printer or a copier, forms an electrostatic latent image on a photoreceptor (e.g., photosensitive drum), and thereafter forms a toner image by attaching toner onto the electrostatic latent image. Then, the image forming apparatus either directly transfers the toner image onto a recording sheet or, alternatively, primary-transfers the toner image onto an intermediate transfer member (e.g., intermediate transfer belt) and thereafter secondary-transfers the toner image onto a recording sheet.
Meanwhile, even after the toner image is transferred, a part of toner remains on the photoreceptor and the intermediate transfer member. Hereinafter, the part of toner remaining as such is simply referred to as “residual toner”. If the residual toner is left uncleaned, the residual toner is melted by heat generated from a fixing device, and is fused onto the surfaces of the photoreceptor and the intermediate transfer belt. If the toner thus fused remains on parts of the photoreceptor and the intermediate transfer member, a newly-formed toner image does not adhere to the parts, causing problems like defective imaging or poor imaging.
Accordingly, a cleaning blade for removing the residual toner is provided on a rotation path of an image carrier such as a photoreceptor or an intermediate transfer member, so that the residual toner on the image carrier is removed by the cleaning blade each time an image forming job is completed.
Also, in order to prevent toner from being fused onto the surface of an intermediate transfer member (i.e., intermediate transfer belt) by heat generated from a fixing device, the following two technologies are known, for example. According to one of the technologies, a cooling fan is provided inside an intermediate transfer member so as to cool the intermediate transfer member (see Japanese Patent Application Publication No. 2005-31503). Also, according to the other technology, the following structure is employed so as to cool the intermediate transfer member. Specifically, an exhaust fan and a cooling fan are provided inside an apparatus. Also, roller members, with which an intermediate transfer member is suspended under tension, are made of heat pipes (Japanese Patent Application Publication No. 2001-296755).
With the aforementioned conventional technologies, it is possible to suppress a rise in the temperature of an intermediate transfer member caused by heat generated from a fixing device, and thereby to effectively prevent the residual toner from being fused onto the intermediate transfer member.
However, according to the conventional technologies, it is necessary to move residual toner to a position at which the residual toner can be removed by a cleaning blade. As a result, an image carrier needs to be rotated for a predetermined time period even after an image forming job is completed. This accelerates abrasion of the image carrier caused by contact with the cleaning blade, thus shortening life of the image carrier.
Also, in the case of cooling an image carrier with a cooling fan and an exhaust fan, the drive of the fans creates noise, and power consumption is increased.